1. Field of the Invention
The present invention relates to an air pollution control apparatus and an air pollution control method that suppress discharge, to the atmosphere, of flue gas discharged from a boiler and the like.
2. Description of the Related Art
Recently, the greenhouse effect of CO2 has been pointed out as a cause of global warming, and a countermeasure against it has become an international urgent task for protecting the global environment. The source of CO2 ranges over every kind of human activities involving burning of fossil fuels, and the trend is toward further demand for the suppression of CO2 discharge. Along with the trend, a method of bringing burnt flue gas from a boiler into contact with amine CO2 absorbing solution and reducing and recovering CO2 in the burnt flue gas, and a method of preserving recovered CO2 without releasing it to the atmosphere have been strenuously studied for use at a power generating facility such as a thermal power plant that uses a large amount of fossil fuels (see, for example, Japanese Patent Application Laid-open No. 2008-62165).
However, no conventional techniques draw the total amount of flue gas from a boiler, a gas turbine, or the like to be discharged from a stack to the atmosphere into a CO2 recovering apparatus. In recovering CO2, it have been demanded to maximize an amount of flue gas drawn in, and not to draw in the atmosphere.
For example, while a fuel gas desulfurization apparatus is generally provided downstream of a boiler for reducing sulfur oxide in flue gas discharged from the boiler, it is proposed to provide a damper or the like that can be opened and closed as a blocking unit in a stack provided upstream of the fuel gas desulfurization apparatus. A schematic of a configuration of a conventional fuel gas treatment facility is shown in FIG. 9. As shown in FIG. 9, in this conventional fuel gas treatment facility 100 in which a desulfurization apparatus is installed as an air pollution control apparatus together with a boiler, the total amount of flue gas 12 discharged from a boiler 11 that is a burning device in, for example, a thermal power plant, is drawn by a blower 13, and SOx in the flue gas 12 is reduced for example by a fuel gas desulfurization apparatus 14. A discharge opening is blocked by providing a damper 16 or the like that can be opened and closed as a blocking unit in a stack 15 so that sulfur oxide is not discharged to the atmosphere. The damper 16 is closed when the fuel gas desulfurization apparatus 14 is operated, and the damper 16 is opened when a flue gas source is running, while the operation performed by the fuel gas desulfurization apparatus 14 is stopped.
However, as shown in FIG. 9, when a blocking unit such as the damper 16 that can be opened and closed is provided in the stack 15, an industrial facility (a gas turbine or the like) provided upstream such as the boiler 11 and a turbine is adversely influenced when the damper 16 is closed while the facility provided upstream such as the boiler 11 and a gas turbine is being operated.
Furthermore, when a blocking unit such as the damper 16 is not provided, as shown in FIG. 10, when the operation performed by the CO2 recovering apparatus, the fuel gas desulfurization apparatus 14, or the like is stopped for example, and the flow rate of flue gas in the stack 15 becomes low, the flue gas 12 having high temperature flows out from a central portion of the inside of the stack 15, and the atmosphere 17 flows in along the inner wall of the stack 15. Thus, the atmosphere 17 flows into the stack 15.
In the case of the stack 15 having a short height, and the stack 15 having a large inner diameter, the flue gas 12 is more prone to flow out from the stack 15, and the atmosphere 17 is more prone to flow into the stack 15.
Accordingly, an appearance of an apparatus has been desired that draws the almost total amount of a large amount of flue gas into a CO2 recovering apparatus, and does not discharge the flue gas to the atmosphere safely and stably even when the operation performed by the CO2 recovering apparatus, the fuel gas desulfurization apparatus, or the like is stopped for example, with a simple structure without providing a blocking unit such as a damper in the stack.
In view of the problems, an object of the present invention is to provide an air pollution control apparatus and an air pollution controls method that can draw, into a CO2 recovering apparatus, almost all amount of flue gas discharged from a stack to the atmosphere stably and safely, and minimizes draw-in of the atmosphere with a simple structure.